Terminal, method and system for performing combination service using terminal capability version

ABSTRACT

A terminal, method and system for providing a CS service, a SIP-based service, or a CSI service, are provided. According to an embodiment, the terminal includes a controller to receive a terminal capability version of at least one target terminal, to compare the received terminal capability version with a previously stored terminal capability version of the at least one target terminal, and to determine whether to request for terminal capability information of the at least one target terminal based on the comparison result, wherein the terminal capability version identifies a version of capabilities of the at least one target terminal.

The present application is a 37 C.F.R. §1.53(b) continuation ofco-pending U.S. patent application Ser. No. 11/443,212 filed May 31,2006, which claims priority on Korean Patent Application No.10-2006-0022404, filed Mar. 9, 2006, and also claims the prioritybenefit of U.S. Provisional Application No. 60/692,665 filed on Jun. 21,2005. The entire contents of all of the above applications are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a combination service forsimultaneously performing two or more services, and particularly, to aterminal, method and system for performing a combination service usingterminal capability version information of the terminal.

2. Discussion of the Related Art

A combination service is a service in which two or more services aresimultaneously performed between a first user and a second user. Thecombination service can also indicate a service for combining at leasttwo or more of a first service based upon a first network, a secondservice based upon a second network, and a third service based upon athird network, and then for simultaneously performing the combinedservices between two or more users.

In order to perform the combination service between the first and secondusers, the first and second users need to respectively understandinformation related to supportable services of the other party and thennegotiate available services therebetween.

Among the different types of combination services, a Combination of a CSservice and an IMS service (CSI) will now be explained as an exemplarycombination service.

The CSI (also referred to herein as CSI service) indicates a service inwhich a Circuit Switched (CS) service and an IP Multimedia Subsystem(IMS) service are combined (united) with each other and then thecombined services are simultaneously performed between two or moreusers/terminals. In the CSI, an IMS session for an IMS service can beadded to a CS call already set between first and second users, or a CScall can be added to an IMS session already set between the first andsecond users. The IMS service, which may be added to the CS call presetbetween the first and second users, can include one or more of IMS basedservices such as an Instant Messaging (IM), a video sharing, a datadelivery, etc. One example of the CSI (combination of CS and IMSservices) can be carrying out a mobile phone conversation (CS service)between a user at mobile terminal A and another user at mobile terminalB and while talking, transmitting a video clip or pictures (IMS service)from the mobile terminal A to the mobile terminal B.

FIG. 1 illustrates a network construction for providing a generalcombination service, for example, the CSI, between first and secondterminals according to a related art. As illustrated in FIG. 1, ageneral network for providing the combination service such as the CSIcan include first and second CS core networks 31 and 32 to support a CSservice for the CSI between a first terminal 10 and a second terminal20, first and second IMS core networks 41 and 42 to support an IMSservice for the CSI between the first and second terminals 10 and 20, afirst Application Server (AS) 43 connected to the first IMS core network41 to perform a particular function of the IMS session for the CSIrelated to the first terminal 10 such as a service based accountingfunction, a second AS 44 connected to the second IMS core network 42 toperform the particular function of the IMS session for the CSI (e.g.,the service based accounting function), a first x-radio access networkxRAN 30 for the first terminal 10 to access the first CS core network 31and the first IMS core network 41 (and vice versa), and a second xRAN 33for the second terminal 20 to access the second CS core network 32 andthe second IMS core network 42 (and vice versa).

The general network for providing the CSI or the like can furtherinclude a first Packet Switched (PS) core network 40 connected betweenthe first xRAN 30 and the first IMS core network 41 to set an IMSsession of the CSI, and a second PS core network 45 connected betweenthe second xRAN 33 and the second IMS core network 42 to set the IMSsession of the CSI.

Each of the first and second CS core networks 31 and 32 can include aMobile Switching Center (MSC), a Visiting Location Register (VLR), and aHome Location Register (HLR).

A general CSI providing method in the general network of FIG. 1 will nowbe explained.

For a CS call between the first and second terminals 10 and 20, data andcontrol signals are exchanged therebetween via the first and second CScore networks 31 and 32. For an IMS session, exchange of data andcontrol signals is performed via the first PS core network 40 and thefirst IMS core network and via the second IMS core network 42 and thesecond PS core network 45.

The first terminal 10 has a function to simultaneously access the firstCS core network 31 and the first PS core network 40, while the secondterminal 20 has a function to simultaneously access the second CS corenetwork 32 and the second PS core network 45.

Before initiating the CSI service between the first and second terminals10 and 20, the first and second terminals 10 and 20 exchange with eachother current radio environment information and terminal capabilityinformation, and thus respectively obtain information related tosupportable services with respect to the other party.

The current radio environment information of the terminal is used asimportant information required to determine user's activities aftersetting the CS call. The radio environment information exchange occursover a CS domain during the CS call setup. The radio environmentinformation is flexible and can be different depending on an environmentwhen the CS call is set. Accordingly, the exchanged radio environmentinformation is used as information valid only during the lifetime of theCS call. The radio environment information may contain informationrelated to whether a terminal can support simultaneous CS and PSservices such as the CSI.

The terminal capability information is information identifyingcapabilities of the terminal, and is used as information for determiningwhether a user who is in communication with another party would callavailable services for that party. The terminal capability informationexchange occurs over an IMS domain.

FIG. 2 illustrates a general method for exchanging terminal capabilityinformation between the first and second terminals 10 and 20 in thegeneral network of FIG. 1.

Referring to FIG. 2, the first terminal 10 sends a Session InitiationProtocol (SIP) OPTIONS message to the second terminal 20, through thefirst and second IMS core networks 41 and 42, to request capabilityinformation of the second terminal 20 (S21). The second terminal 20 thenstores address information of the first terminal 10 contained in thereceived OPTIONS message (S22), and then sends a 200 OK message to thefirst terminal 10 in response to the SIP OPTIONS message. The 200 OKmessage contains the terminal capability information of the secondterminal 20 (S23).

The first terminal 10 having received the 200 OK message stores theterminal capability information of the second terminal 20 contained inthe 200 OK message (S24).

On the other side, in case that the second terminal 20 has received theOPTIONS message from the first terminal 10 but has not sent an OPTIONS(SIP OPTIONS) message to the first terminal 10 for requesting theterminal capability information of the first terminal 10, the secondterminal 20 determines to send the OPTIONS message to the first terminal10 (S25). Upon receiving the OPTIONS message for requesting the terminalcapability information of the first terminal 10 from the second terminal20, the first terminal 10 stores the address information of the secondterminal 20 contained in the received OPTIONS message (S26 and S27), andsends a 200 OK message to the second terminal 20 in response to thereceived OPTIONS message (S28). This 200 OK message contains thecapability information of the first terminal 10.

The second terminal 20 then stores the capability information of thefirst terminal 10 contained in the 200 OK message sent from the firstterminal 10 (S29).

Accordingly, the terminal capability information of the first terminal10 and that of the second terminal 20 exchanged therebetween are storedin the second terminal 20 and the first terminal 10, respectively, so asto provide a fast service setup and to reduce network loads during thesubsequent communication therebetween.

According to the related art method discussed above, in order for aparticular terminal to obtain terminal capability information of itscounterpart terminal, the particular terminal needs to send an OPTIONSmessage to the counterpart terminal to thus request the terminalcapability information of the counterpart terminal, and receive from thecounterpart terminal a response message containing the terminalcapability information of the counterpart terminal. Based upon thismethod, the terminal sends an OPTIONS message once (e.g., for a callsetup) a counterpart terminal and stores therein the received terminalcapability information of its counterpart terminal for subsequent use.

Hence, even in case where the capability information (capabilities) ofthe counterpart terminal has not changed, the terminal still sends anOPTIONS message once to the counterpart terminal (e.g., for a callsetup) to perform the operation of receiving the unchanged terminalcapability information of the counterpart terminal. However, it is notnecessary since the capability information of the counterpart terminalhas not changed and is already stored in the terminal from the previousOPTIONS operation. Further, such an operation may increase the load ofthe network.

In general, on the other side, the actual capability information relatedto the terminal may dynamically be updated. Cases in which the terminalcapability information (capabilities) may be changed (updated) accordingto the related art will be explained as follows.

There are three cases in which the actual capability information of theterminal may be changed in that terminal. Namely, there exist a firstcase where various devices (e.g., a camera, etc.) have dynamically beenattached to the terminal and detached therefrom, a second case where theterminal has been registered in an IMS service, and a third case wherethe terminal has updated its current capability information bydownloading a new codec using a downloading service.

After the change of the actual capability information of the terminal,if a cache of the terminal is not updated together due to the poweron/off, SIM swap off, time out, and the like, all of which are relatedto the terminal, then the capability information of the terminal asstored in the cache of that terminal may not accurately reflect theactual capability information (capabilities) of that terminal. Then,since the counterpart terminal receives the stored capabilityinformation from the cache of the terminal, the actual capabilityinformation of the terminal will not be consistent with the capabilityinformation of the terminal as stored in the cache of the counterpartterminal. That is, due to the dynamic change, the actual capabilities ofthe terminal may not be known to the counterpart terminal.

Accordingly, when the counterpart terminal desires to use a CSI with theterminal later, the counterpart terminal would confirm that thecapability information of the terminal has already been stored in thecache of the counterpart terminal, and then immediately send an INVITEmessage to the terminal after a radio capability exchange therebetween,without performing the sending of the OPTIONS message (i.e., the OPTIONSprocess) to obtain the capability information of the terminal. Thecounterpart terminal accordingly requests a PoC service from theterminal. However, since the capabilities of the terminal have changed(e.g., the terminal is not fully capable of performing a PoC service),the terminal de-registers the PoC service, the PoC service fails to berequested, and thereby the counterpart terminal must re-perform theOPTIONS process to obtain the capability information of the terminal.Thus, the previously stored terminal capability information cannot beused in the related art.

In addition, in the current mobile communications system, one subscribercan have multiple terminals, and one public user identity can be usedsimultaneously at several subscriber identity modules (SIMs) of theterminals. Namely, one subscriber shares a Mobile Station InternationalSubscriber Directory Number (MSISDN) with other terminals for use. Incase of a cache which uses only the public user identity, when a requestis received, it may not be possible for the receiving terminal torecognize which one of the multiple terminals of the counterpart hassent the request because of the use of the public user identity.Accordingly, the combination service (e.g., the CSI) may not be normallyperformed with the terminal that has actually sent the request.

SUMMARY OF THE INVENTION

Therefore, an object of the present invention is to provide a terminalor user equipment (UE), method and system for performing a combinationservice using a terminal capability version, which are capable ofsimplifying a terminal capability information exchange procedure and asignaling procedure during a connection set-up for a combination serviceby allowing each terminal to send a terminal capability version thereof.

Another object of the present invention is to provide a terminal/UE,method and system for performing a combination service using a terminalcapability version in which whenever terminal capability information ofeach terminal is changed, each terminal maintains a terminal capabilityversion thereof with a unique value and sends the terminal capabilityversion during a connection set-up for a combination service, wherebywhether the terminal capability information of another party has beenchanged can be correctly determined and the efficiency of a cache usagecan be increased by maintaining consistent information in the caches ofthe involved terminals.

Another object of the present invention is to provide a terminal, systemand method of providing a CS service, a SIP-based service (e.g., an IMSservice, etc.), or a CSI service, which address the limitations anddisadvantages associated with the related art.

To achieve these and other advantages and in accordance with the purposeof the present invention, as embodied and broadly described herein,there is provided according to one aspect a method for performing acombination service in a method for simultaneously performing differentservices among two or more terminals, the method comprising: exchangingterminal capability versions when requesting a service connection; andcomparing a received terminal capability version with a stored terminalcapability version to selectively performing a terminal capabilityinformation exchange procedure and a service connection setup procedure.

According to another aspect of the present invention, in a system forsimultaneously performing different services among two or moreterminals, a method for performing a combination service can comprise:generating a terminal capability version based upon terminal capabilityinformation; and sending the terminal capability version when requestinga service connection.

To achieve these and other advantages and in accordance with the purposeof the present invention, according to another aspect, in an apparatusfor performing a combination service with at least one or moreterminals, a terminal can comprise a storage unit for storing at leastterminal capability version and terminal capability information of acounterpart terminal, and a processor for sending a terminal capabilityversion the terminal itself to the counterpart terminal when connectingthe service and comparing a terminal capability version of thecounterpart terminal, which is received from the counterpart terminal,with a stored terminal capability version of the counterpart terminal toselectively perform a terminal capability information exchange procedureand a service connection setup procedure.

According to still another aspect of the present invention, in a methodfor simultaneously performing first and second services among two ormore terminals, a method for performing a combination service cancomprise: sending a call setup message for the first service whichincludes a first capability version from an originating terminal to areceiving (terminating) terminal; receiving, by the originatingterminal, a connection response message including a second capabilityversion from the receiving terminal; and sending a session connectionrequest message for the second service from the originating terminal tothe receiving terminal when it is confirmed that the received secondcapability version is equal to a stored capability version of thereceiving terminal.

According to another aspect, the present invention provides a terminalcapable of providing a circuit switched (CS) service, a sessioninitiation protocol (SIP)-based service, or a CSI service which is acombination of the CS service and an IP multimedia subsystem (IMS), theterminal comprising: a controller to generate a terminal capabilityversion based on at least terminal capability information of theterminal, and to transmit the terminal capability version to at leastone target terminal, wherein the terminal capability version identifiesa version of capabilities of the terminal.

According to another aspect, the present invention provides a terminalfor providing a circuit switched (CS) service, a session initiationprotocol (SIP)-based service, or a CSI service which is a combination ofthe CS service and an IP multimedia subsystem (IMS), the terminalcomprising: a controller to transmit a terminal capability version ofthe terminal to at least one target terminal and to receive a terminalcapability version of the at least one target terminal, during an IMsession set-up or during a CS call set-up, wherein the terminalcapability version identifies a version of capabilities of thecorresponding terminal.

According to another aspect, the present invention provides a terminalcapable of providing a circuit switched (CS) service, a sessioninitiation protocol (SIP)-based service, or a CSI service which is acombination of the CS service and an IP multimedia subsystem (IMS), theterminal comprising: a controller to receive a terminal capabilityversion of at least one target terminal, to compare the receivedterminal capability version with a previously stored terminal capabilityversion of the at least one target terminal, and to determine whether torequest for terminal capability information of the at least one targetterminal based on the comparison result, wherein the terminal capabilityversion identifies a version of capabilities of the at least one targetterminal.

According to another aspect, the present invention provides a systemcapable of providing a circuit switches (CS) service, a sessioninitiation protocol (SIP)-based service, or a CSI service which is acombination of the CS service and an IP multimedia subsystem (IMS), thesystem comprising: a first terminal and a second terminal to exchangeterminal capability versions thereof to each other during a servicesetup, each terminal capability version identifying a version ofcapabilities of the corresponding terminal.

According to another aspect, the present invention provides a method forproviding a circuit switched (CS) service, a session initiation protocol(SIP)-based service, or a CSI service which is a combination of the CSservice and an IP multimedia subsystem (IMS), the method comprising:generating, by a terminal, a terminal capability version based on atleast terminal capability information of the terminal; and transmitting,by the terminal, the generated terminal capability version to at leastone target terminal, wherein the terminal capability version identifiesa version of capabilities of the terminal.

According to another aspect, the present invention provides a method forproviding a circuit switched (CS) service, a session initiation protocol(SIP)-based service, or a CSI service which is a combination of the CSservice and an IP multimedia subsystem (IMS), the method comprising:transmitting, by a terminal, a terminal capability version of theterminal to at least one target terminal during an IM session set-up ora CS call set-up; and receiving, by the terminal, a terminal capabilityversion of the at least one target terminal from the at least one targetterminal during the IM session set-up or the CS call set-up, wherein theterminal capability version identifies a version of capabilities of thecorresponding terminal.

According to another aspect, the present invention provides a method forproviding a circuit switched (CS) service, a session initiation protocol(SIP)-based service, or a CSI service which is a combination of the CSservice and an IP multimedia subsystem (IMS), the method comprising:receiving, by a terminal, a terminal capability version of at least onetarget terminal; comparing, by the terminal, the received terminalcapability version with a previously stored terminal capability versionof the at least one target terminal; and determining, by the terminal,whether to request for terminal capability information of the at leastone target terminal based on the comparison result, wherein the terminalcapability version identifies a version of capabilities of the at leastone target terminal.

According to another aspect, the present invention provides a method forproviding a circuit switched (CS) service, a session initiation protocol(SIP)-based service, or a CSI service which is a combination of the CSservice and an IP multimedia subsystem (IMS), the method comprising:exchanging, by first and second terminals, a terminal capability versionof the first terminal and a terminal capability version of the secondterminal to each other during a service setup, each terminal capabilityversion identifying a version of capabilities of the correspondingterminal.

According to another aspect, the present invention provides a method forproviding a circuit switched (CS) service, a session initiation protocol(SIP)-based service, or a CSI service which is a combination of the CSservice and an IP multimedia subsystem (IMS), the method comprising:storing, in a first terminal during a previous CSI service, a publicuser ID of a second terminal, terminal capability information of thesecond terminal, and a terminal capability version of the secondterminal, wherein the terminal capability version of the second terminalidentifies a version of capabilities of the second terminal; storing, inthe second terminal during a previous CSI service, a public user ID ofthe first terminal, terminal capability information of the firstterminal, and a terminal capability version of the first terminal,wherein the terminal capability version of the first terminal identifiesa version of capabilities of the first terminal; updating the terminalcapability information of the first terminal if the first terminal'scapability information is dynamically changed; generating, by the firstterminal, a new terminal capability version of the first terminal basedon at least the updated terminal capability information of the firstterminal; transmitting an INVITE message for an IMS session setup fromthe first terminal to the second terminal, the INVITE message includingthe new terminal capability version of the first terminal; comparing, bythe second terminal, the received terminal capability version of thefirst terminal with the stored terminal capability version of the firstterminal; and selectively performing, by the second terminal, a terminalcapability information request procedure based on the comparison result.

According to another aspect, the present invention provides a method forproviding a circuit switched (CS) service, a session initiation protocol(SIP)-based service, or a CSI service which is a combination of the CSservice and an IP multimedia subsystem (IMS), the method comprising:storing, in a first terminal during a previous CSI service, a publicuser ID of a second terminal, terminal capability information of thesecond terminal, and a terminal capability version of the secondterminal, wherein the terminal capability version of the second terminalidentifies a version of capabilities of the second terminal; storing, inthe second terminal during a previous CSI service, a public user ID ofthe first terminal, terminal capability information of the firstterminal, and a terminal capability version of the first terminal,wherein the terminal capability version of the first terminal identifiesa version of capabilities of the first terminal; updating the terminalcapability information of the first terminal if the first terminal'scapability information is dynamically changed; generating, by the firstterminal, a new terminal capability version of the first terminal basedon at least the updated terminal capability information of the firstterminal; transmitting a call setup message for a CS call setup of acurrent CSI service from the first terminal to the second terminal;transmitting a call connect message from the second terminal to thefirst terminal in response to the call setup message, the call connectmessage including a current terminal capability version of the secondterminal; selectively performing, by the first terminal, a terminalcapability information request procedure based on a comparison of theterminal capability version of the second terminal included in thereceived call connect message with the stored terminal capabilityversion of the second terminal; transmitting an INVITE message from thefirst terminal to the second terminal, wherein the new terminalcapability version of the first terminal is included in the transmittedINVITE message and/or the transmitted call setup message; andselectively performing, by the second terminal, a terminal capabilityinformation request procedure based on a comparison of the terminalcapability version of the first terminal included in the received callconnect message and/or the INVITE message with the stored terminalcapability version of the first terminal.

The foregoing and other objects, features, aspects and advantages of thepresent invention will become more apparent from the following detaileddescription of the present invention when taken in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this specification, illustrate embodiments of the invention andtogether with the description serve to explain the principles of theinvention.

In the drawings:

FIG. 1 is a diagram illustrating a network construction for providing ageneral combination service between first and second terminals;

FIG. 2 is a diagram illustrating a general method for exchangingterminal capability information between the first and second terminalsof FIG. 1;

FIG. 3 is a diagram illustrating a terminal equipped with a storage unitfor storing a terminal capability version according to current terminalcapability information according to an embodiment of the presentinvention;

FIG. 4 is a diagram illustrating different examples of a method ofgenerating a unique terminal capability version which correspond tocurrent terminal capability information according to the presentinvention;

FIG. 5 is a diagram illustrating a method for performing a combinationservice using terminal capability versions according to a firstembodiment of the present invention;

FIG. 6 is a diagram illustrating a method for performing a combinationservice using terminal capability versions according to a secondembodiment of the present invention; and

FIGS. 7 and 8 are diagrams illustrating a method for performing acombination service using terminal capability versions according to athird embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Description will now be given in detail of the present invention, withreference to the accompanying drawings.

Explanations will be given for a terminal, method and system forperforming a combination service using a terminal capability versionaccording to the preferred embodiments of the present invention withreference to the attached drawings hereafter.

In the present disclosure of the present invention, the term “capabilityversion” of a terminal (or terminal capability information) is versioninformation that identifies the version of the capabilities (capabilityinformation) of the terminal. For instance, a terminal capabilityversion is a unique value that identifies the current version (set) ofcapabilities that the terminal has.

In the present invention, at least the current capability information ofa terminal is used to generate a unique terminal capability version.Upon setting a combination service connection between at least twoterminals, the terminals can send their capability versions to the otherterminals using a SIP signaling message, or send their capabilityversions to the other terminals when sending current radio capabilityenvironment information during a call set-up.

Accordingly, a first terminal compares the pre-stored capability versionof a second terminal with a currently received capability version of thesecond terminal to determine whether the terminal capability informationof the second terminal has been updated, and thereby selectivelyperforms a terminal capability information exchange procedure and aservice connection setup procedure. For instance, if the comparison ofthe capability versions indicates that the terminal capabilityinformation of the second terminal has changed, then the first terminalperforms the terminal capability information request/exchange procedureto obtain the updated terminal capability information of the secondterminal from the second terminal. As a result, the first terminalrequests for the terminal capability information of the second terminalonly when the first terminal determines the terminal capabilityinformation of the second terminal has been changed/updated.

Now, the terminal capability information of each terminal will beexplained according to the present invention. The terminal capabilityinformation (i.e., capability set or set of capabilities) may include atleast one or more of the following items:

-   -   Screen capabilities, colors, resolution, sizes and the like    -   Memory/storage capacity (for downloading video, music, email        attachment, etc.)    -   Capability to stream/download video and still images    -   Codec types (EFR, AMR, MPEG4, H.264, MPS, etc.)    -   Device software/firmware release/version.    -   Calendar storage capacity    -   Contacts storage capacity    -   Notes storage capacity    -   Operating System of devices (terminals)    -   Browser types (WAP 1.2/2.0, HTML, etc.)    -   MExE classmark (mobile execution environment)    -   USIM application toolket capabilities (release/version)    -   Data rate capability    -   SIP call control protocol    -   Number of simultaneous PDP contexts supported    -   Number of APNs supported

In the present invention, such terminal capability information of aterminal alone or with some other information is used to generate aunique terminal capability version. For instance, the terminal can useonly its terminal capability information to generate the terminalcapability version. As an alternative, the terminal can use its terminalcapability information, a private user Identity (ID) associated with theterminal, and a public user ID associated with the terminal, to generatethe unique terminal capability version. Hence, if one user has severalterminals and the several terminals use the same public user ID, it ispossible to correctly distinguish the terminal capability information ofeach terminal using the same public user ID based upon the correspondingterminal capability version of each terminal. As another alternative,the terminal can use its terminal capability information and a publicuser ID associated with the terminal to generate the unique terminalcapability version.

According to the present invention, in order to generate the uniqueterminal capability version based upon at least the terminal capabilityinformation, the terminal can use a hash function or may use othermethods.

Furthermore, the terminal capability version can have a unique value ofone byte (or some other data size) according to the terminal capabilityinformation (i.e., the capability sets). When the terminal capabilityversion has the value of one byte, 256 different terminal capabilityinformation can be represented. The number of terminal capabilityversions to be represented can be enlarged or decreased according to thefeatures of an application program.

The unique values of the terminal capability versions can be indicatedin a bit form or a digit form. The terminal capability version can alsohave a unique value in a UCV-XX (UE Capability Version-XX) form. Here,the “XX” may be a 2-digit hexadecimal number as shown in Table 1 below.The “XX” may have values belonging to a range from “00” to a hexadecimalnumber “FF”. The terminal capability version having the UCV-XX form maybe generated by a CSI user agent (CUV) based upon the terminalcapability information. The hexadecimal number “XX” is coded in theterminal (i.e., UE) capability version information element.

TABLE 1 8 7 6 5 4 3 2 1 UE capability version IEI octet 1 (informationelement identifier) UE capability UE capability octet 2 version digit 2version digit 1

Each terminal (UE) stores its own terminal capability version accordingto at least its terminal capability information in a storage unitassociated with that terminal, and also stores the terminal capabilityversion(s) of other terminals. FIG. 3 illustrates a terminal 100 or 200equipped with such a storage unit for storing the terminal capabilityversion(s) according to the present invention. The storage unit can be amemory or cache 160, or a Universal Subscriber Identity Module (USIM)170. Both the internal storage and/or the external/detachable storage ofthe terminal can store therein the current capability version of theterminal as well as the capability version(s) of other terminals. Eachterminal also includes a controller/processor 150 and other componentsknown in the related art terminals or the like such a user input unit, adisplay unit, an audio unit, a network interface, etc.

The terminal capability information of each terminal, on the other hand,can be updated dynamically. The terminal capability information of theterminal can be updated, for example, when several devices (e.g., acamera, etc.) were dynamically attached to the terminal or detachedtherefrom, when the terminal registered in an IP Multimedia Subsystem(IMS) service or de-registered therefrom, when the terminal uses adownloading service to download a new codec, or the like. The presentinvention in fact can cover any situation in which the terminalchanges/updates its capabilities (capability information). In all suchsituations, the terminal generates a unique terminal capability versioneach time the terminal capability information of the terminal is updated(changed), and the generated new terminal capability version is storedin the storage unit of the terminal as the current terminal capabilityversion of the terminal.

FIG. 4 illustrates different examples of a method of generating a uniqueterminal capability version based on at least the current terminalcapability information according to the present invention. This methodcan be performed by the terminal, e.g., the terminal 100, 200 of FIGS. 3and 5-7.

As shown in FIG. 4, a known hash function can be used to generate aunique terminal capability version for each terminal. For using the hashfunction, the terminal inputs only the updated terminal capabilityinformation into the hash function to generate a unique terminalcapability version. As an alternative, the terminal can input a privateuser ID and/or a public user ID into the hash function together with theupdated terminal capability information so as to generate a uniqueterminal capability version. For instance, a unique terminal capabilityversion can be generated using a hash or other encryption function bythe following (a) or (b): (a) the terminal capability information of theterminal, a public user ID associated with the terminal, and a privateuser ID associated with the terminal; or (b) the terminal capabilityinformation of the terminal and a public user ID associated with theterminal.

In the first example of FIG. 4, if the current terminal capabilityinformation (i.e., first terminal capability information) of theterminal is a capability set including screen capabilities with 256colors and a 640×486 resolution, a 256 MB memory, an Enhanced Full Rate(EFR), an Adaptive Multi-Rate (AMR), Motion Picture Experts Group 4(MPEG4), a codec type including H.264, and a WAP 1.2 browser type, thenthe terminal inputs the first terminal capability information into ahash function to generate a first terminal capability version having aunique value. As illustrated in FIG. 4, the first terminal capabilityversion may be ‘0100 1000’, for example.

In the second example of FIG. 4, when a camera is attached to theterminal and thus the capability of the terminal is changed, theterminal inputs its current terminal capability information (i.e.,second terminal capability information) having a camera function addedthereto into a hash function to generate a second terminal capabilityversion having a unique value. Here, the generated second terminalcapability version may be ‘1011 1001’, for example.

In the third example of FIG. 4, when the browser type of the terminal isupdated to a WAP 2.0, the terminal uses its current terminal capabilityinformation (i.e., third terminal capability information) of whichbrowser type has been updated to generate a third terminal capabilityversion having a unique value. The third terminal capability version maybe ‘0101 1000’, for example.

As aforementioned, whenever the terminal capability information of theterminal is dynamically changed, the terminal changes its terminalcapability version to have a new unique value based on at least thechanged terminal capability information. Hence, it is possible to easilyconfirm whether or not the terminal capability information of theterminal has been changed based upon whether or not the terminalcapability version of the terminal has been changed.

In the present invention, upon exchanging the terminal capabilityinformation of the terminal using a Session Initiation Protocol (SIP)signaling message (e.g., an OPTIONS message, an INVITE message, etc.) orupon exchanging current radio capability environment information duringa call setup (e.g., a call setup message), each terminal sends itsterminal capability version to other terminal(s). The terminalcapability versions of the other terminal(s) exchanged are stored ineach terminal together with the exchanged terminal capabilityinformation and the public user ID associated with the correspondingterminal.

Afterwards, upon setting a service connection for a combination serviceincluding, but not limited to, the CSI, if the terminal capabilityversion value of a terminal B stored in a terminal A is different fromthe terminal capability version value of the terminal B currentlyreceived by the terminal A according to the comparison therebetween,then the terminal A can notify the terminal B that the stored terminalcapability version of the terminal B needs to be updated and alsorequest for the current capability information of the terminal B. Theterminal capability version value of the terminal B as stored in theterminal A may be different from the terminal capability version valueof the terminal B currently received by the terminal A in cases where astorage unit (e.g., an SIM or USIM) of the terminal A has been replaced,the terminal capability information of the terminal B has dynamicallybeen changed, etc.

On the other hand, as a method for maintaining a consistency of thestorage unit of the terminal for storing the terminal capabilityinformation, the present invention provides a method in which when theterminal capability information of the terminal has dynamically changed,the changed contents are sent to another terminal with the public userID stored in the storage unit of the terminal using a method such asLBS.

FIG. 5 illustrates a method for performing a combination service using aterminal capability version according to a first embodiment of thepresent invention. The method of FIG. 5 includes the method ofgenerating a unique terminal capability version as discussed above. Themethod of FIG. 5 can be implemented in the system and device of FIGS. 1and 3 or in other similar or suitable device/system. The processes to beperformed by the terminal 100 or 200 can be performed and/or controlledby the controller 150 of the terminal 100 or 200.

As illustrated in FIG. 5, in order to perform the combination serviceincluding at least a first service and a second service, a system forperforming a combination service using a terminal capability version caninclude first and second terminals 100 and 200 which exchange theirterminal capability versions to each other when connecting for the firstservice. Each terminal compares the received terminal capability versionof the other terminal with a stored terminal capability version of theother terminal, and, if the two terminal capability versions are notequal, requests updated terminal capability information from theterminal for reception.

The system may further include a first service network for providing thefirst service to the first and second terminals 100 and 200, and asecond service network for providing the second service to the first andsecond terminals 100 and 200. When the first service is a SIP-basedservice such as an IMS service, the first service network may include afirst IMS core network 410 for providing the IMS service to the firstterminal 100, and a second IMS core network 420 for providing the IMSservice to the second terminal 200. When the second service is a CSservice, the second service network may include a first CS core network(e.g., 31 in FIG. 1) for providing the CS service to the first terminal100, and a second core network (e.g., 32 in FIG. 1) for providing the CSservice to the second terminal 200. The system can also include othercomponents such as first and second PS core networks, first and secondxRANs, first and second ASs, etc. All the components of the system areoperatively coupled and/or configured.

The storage unit 160, 170 of each terminal 100, 200 can store thereinits own terminal capability version and terminal capability information,the terminal capability version and terminal capability information ofother terminal(s) (e.g., obtained from a previous service connectionwith the other terminal(s)), and its own public user ID and a publicuser ID of the other parties. The controller/processor 150 of eachterminal 100, 200 sends its terminal capability version to anotherparty/terminal when connecting for the first service, compares theterminal capability version of the another party received from theanother party with the terminal capability version of the another partystored in the storage unit, and selectively performs a terminalcapability exchange procedure and a service connection setup procedurebased on the comparison results.

With reference to FIG. 5, the method for performing the combinationservice using the terminal capability version according to the firstembodiment of the present invention will now be explained. FIG. 5illustrates an example of the method in which an IMS session is setfirst and thereafter a CS call is set when setting a combination serviceconnection, namely, the CSI connection. This method is also applicablewhen setting an IMS session only, i.e., no CS call is set after the IMSsession is set.

As shown in FIG. 5, the first terminal 100 and the second terminal 200exchange their terminal capability information with each other using acombination service (e.g., a current CSI service connection) andthereafter respectively store the exchanged terminal capabilityinformation, e.g., in the cache of the respective terminal. The firstand second terminals 100 and 200 respectively store, e.g., in itsstorage unit, at least a public user ID of the other party (associatedwith the other terminal), a terminal capability version of the otherterminal, and terminal capability information of the other terminal(S51). The terminal capability version of each terminal is calculated asdiscussed above, e.g., based on at least the capability information ofthe terminal. The terminal capability information may include a codec tobe supportable, a file format, and the like, for example. In addition,each of the first and second terminals 100 and 200 also stores thereinits own public user ID, its terminal capability version (value), itsterminal capability information, etc. As an example, the currentcapability versions of the first and second terminals are V.0.12 andV.3.3. at step S51.

Then, the first and second terminals 100 and 200 perform a data exchangeand a voice exchange using the current session/connection for the CSIservice, and thereafter release the current CSI session/connectionbetween the first and second terminals 100 and 200 (S52). Here, thefirst terminal 100 can store therein the public user ID of the secondterminal 200, the terminal capability version of the second terminal200, and the terminal capability information of the second terminal 200,all of which have been exchanged during the CSI setup procedure, andalso stores therein its terminal capability version. The second terminal200 can also store such information related to the terminal capabilityinformation of the first terminal 100 using the same method. Theinformation stored in the first terminal 100 is used when the firstterminal 100 expects to perform another CSI service with the secondterminal 200 later.

Afterwards, the terminal capability information of each terminal, e.g.,the terminal capability information of the first terminal 100, may bechanged due to various reasons. For instance, the terminal capabilityinformation of the first terminal 100 may be changed in cases where IMSservices (e.g., PoC (Push-to-talk Over Cellular), IM, broadcasting,etc.) were registered or de-registered, multimedia devices (e.g., acamera, etc.) were dynamically attached to the first terminal 100 ordetached therefrom, a downloading service was used to modify a new codecor a supportable file format, or a version of a Multimedia Messageservice (MMS) was updated (S53).

When the terminal capability information of the first terminal 100 ischanged, the first terminal 100 changes its terminal capability version,e.g., based on at least the updated capability information of the firstterminal 100 (S54). As a result, the current terminal capability versionof the first terminal 100 is now different from the terminal capabilityversion of the first terminal 100 stored in the second terminal 200. Forexample, since the terminal capability version of the first terminal 100has been changed from V.0.12 to V.1.12 due to the change of its terminalcapability information, the current terminal capability version of thefirst terminal 100 is now different from the terminal capability versionof the terminal 100 (i.e., V.0.12) currently stored in the secondterminal 200 (S55).

Thereafter, when the first terminal 100 desires to perform a CSI servicewith the second terminal 200, the first terminal 100 attempts to asession connection for an IMS service. Here, the first terminal 100confirms that it already has stored information related to the secondterminal 200, and immediately performs an IMS session setup by sendingan INVITE message without exchanging terminal capability informationtherebetween. The INVITE message includes therein the current terminalcapability version (i.e., V.1.12) of the first terminal 100. The firstterminal 100 can generate the INVITE message with reference to theinformation of the second terminal 200 stored therein and sends thegenerated INVITE message to the second terminal 200. The information ofthe second terminal 200 that is stored in the first terminal 100 mayinclude at least the public use ID and the terminal capabilityinformation of the second terminal 200.

The INVITE message is sent from the first terminal 100 to the secondterminal 200 via the first IMS core network 410 and the second IMS corenetwork 420 (S56).

The second terminal 200 obtains the terminal capability version of thefirst terminal 100 included in the received INVITE message. The secondterminal 200 compares the received terminal capability version (e.g.,V.1.12) of the first terminal 100 with the terminal capability version(e.g., V.0.12) of the first terminal 100 pre-stored in the secondterminal 200. The second terminal 200 selects and performs one theterminal capability information exchange procedure and a responsesending procedure with respect to the IMS session connection requestaccording to the results of the comparison (S57).

For instance, If the received terminal capability version of the firstterminal 100 is equal to the pre-stored terminal capability version ofthe first terminal 100, the second terminal 200 determines that thecurrent terminal capability information of the first terminal 100 hasnot been changed after performing the previous CSI service, and thussends a 200 OK message in response to the INVITE message. However, ifthe received terminal capability version of the first terminal 100 isdifferent from the pre-stored terminal capability version of the firstterminal 100, the second terminal 200 determines that the currentterminal capability information of the first terminal 100 has beenchanged after performing the previous CSI service, and thus performs theterminal capability information exchange procedure to obtain the currentcapability information of the first terminal 100. That is, the secondterminal 200 sends an OPTIONS request message (SIP message) to the firstterminal 100 to request the changed terminal capability information ofthe first terminal 100. The OPTIONS request message may include thecurrent terminal capability version of the second terminal 200. TheOPTIONS request message is sent from the second terminal 200 to thefirst terminal 100 via the first and second IMS core networks 410 and420 (S58).

The first terminal 100 having received the OPTIONS request message sendsits terminal capability information to the second terminal 200. Thesecond terminal 200 then stores the newly changed terminal capabilityinformation of the first terminal 100. Accordingly, each of the firstand second terminals 100 and 200 obtains and stores the current terminalcapability information and the current terminal capability version ofthe other terminal.

Afterwards, if desired the first terminal 100 and the second terminal200 can perform a CS call setup procedure through first and second CScore networks to provide the CSI service. The CS call setup procedurefor the CSI service is known.

Accordingly, each time the terminal capability information of a terminalis changed, the terminal capability version can be maintained with aunique value, and then sent to one or more parties, whereby it ispossible to determine whether or not the terminal capability informationof each terminal has been changed and then the terminal capabilityinformation can be requested if the terminal capability information haschanged based on the determination, thereby stably using the storageunit of each terminal. The present invention thus provides an effectiveand efficient system and method for exchanging terminal capabilityinformation for a combination service such as a CSI.

FIG. 6 illustrates a method for performing a combination service using aterminal capability version according to a second embodiment of thepresent invention. The method of FIG. 6 includes the method ofgenerating a unique terminal capability version as discussed above. Themethod of FIG. 6 can be implemented in the system and device of FIGS. 1and 3 or in other similar or suitable device/system. The processes to beperformed by the terminal 100 or 200 can be performed and/or controlledby the controller 150 of the terminal 100 or 200.

As illustrated in FIG. 6, a system for performing the combinationservice using the terminal capability version according to the presentinvention may include the first and second terminals 100 and 200, thefirst and second IMS core networks 410 and 420 and the first and secondCS core networks 310 and 320. FIG. 6 illustrates a method for performinga combination service in which when the combination service is the CSIservice, the CS call is first set and thereafter the IMS session is set.

Step S61 is performed using the same method used for S51 and S52 of FIG.5. Upon completing the CSI service between the first terminal 100 andthe second terminal 200, the public user ID, the terminal capabilityinformation, and the terminal capability version of each terminal arestored in the other one of the first and second 100 and 200 (S61). Thatis, steps S61 is the same or similar to steps S51 and S52 of FIG. 5.

As an example, it is assumed that information as follows is stored inthe first terminal 100:

Second terminal; bobs@lge.com; text-audio-video-mpeg-typeofcodec-etc;V.3.3 wherein the public user ID of the second terminal 200, e.g., URI,is bobs@lge.com, supportable terminal capability information of thesecond terminal 200 indicates text, audio, video, mpeg and variouscodecs, and the current terminal capability version of the secondterminal 200 is V.3.3.

Thereafter, each of the first and second terminals 100 and 200 candynamically change their terminal capability information, e.g., in casesof registering and de-registering of the IMS service, attaching anddetaching of multimedia devices, etc. As an example, an explanation willbe given below for a case where the terminal capability information ofthe first terminal 100 has been changed.

When the terminal capability information of the first terminal 100 ischanged, the first terminal 100 uses at least the changed terminalcapability information (with or without additional information such aspublic user ID and/or private user ID) to generate a new terminalcapability version having a unique value (S62 and S63). As an example,the previous terminal capability version of the first terminal 100 wasV.0.12, whereas the newly generated (changed) terminal capabilityversion is V.1.12.

Afterwards, when the first terminal 100 wants to firstly set a CS callto perform a CSI service with the second terminal 200, the firstterminal 100 sends a CS call setup message (e.g., a SETUP message) tothe second terminal 200 (S64). The CS call setup message can include atleast the terminal capability version of the first terminal 100. Forexample, the current terminal capability version (value) of the firstterminal 100, which is V.1.12, is included in the call setup message.The call setup message is sent from the first terminal 100 to the secondterminal 200 via the first and second CS core networks 310 and 320.

The second terminal 200 then sends a connection message CONNCECT to thefirst terminal 100 in response to the call setup message (S65). Theconnection message CONNECT may include at least the terminal capabilityversion (e.g., V.3.3) of the second terminal 200. The connection messageCONNECT can be sent from the second terminal 200 to the first terminal100 via the first and second CS core networks 310 and 320.

After completing the CS call setup, in order to set an IMS session forthe CSI service, the first terminal 100 compares the pre-stored terminalcapability version (e.g., V.3.3) of the second terminal 200 with theterminal capability version (e.g., V.3.3) of the second terminal 200received when setting the CS call (S66). According to the results of thecomparison, the first terminal 100 selects and performs either theterminal capability information exchange procedure or immediately theIMS session setup procedure.

For instance, at step S66, if the previously-stored terminal capabilityversion of the second terminal 200 is different from the receivedterminal capability version of the second terminal 200, the firstterminal 100 determines that the terminal capability information of thesecond terminal 200 has been changed since performing a previous CSIservice. Thus the first terminal 100 performs the terminal capabilityinformation exchange/transmission procedure, wherein the first terminal100 sends a SIP's OPTIONS request message to the second terminal 200 inorder to request and receive the changed terminal capability informationof the second terminal 200 from the second terminal 200 (not shown inFIG. 6, but similar to the OPTIONS procedure of FIG. 2).

However, at step S66, if the pre-stored terminal capability version(e.g., V.3.3) of the second terminal 200 is equal to the receivedterminal capability version (e.g., V.3.3) of the second terminal 200(which is the case in the present example), the first terminal 100determines that the current terminal capability information of thesecond terminal 200 is equal to the terminal capability information ofthe second terminal 200 at the time of performing the previous CSIservice. That is, there is no change in the terminal capabilityinformation of the second terminal 200. Hence, the first terminal 100does not send the OPTIONS request message for the terminal capabilityinformation exchange to the second terminal 200, but instead sends anINVITE message to the second terminal 100 for requesting an IMS sessionsetup thereto (S67). Here, the INVITE message may include at least theterminal capability version of the first terminal 100. Here, theterminal capability version of the first terminal 100 is V.1.12, forexample. The INVITE message is sent to the second terminal 200 via thefirst and second IMS core networks 410 and 420.

The second terminal 200 then compares the terminal capability version ofthe first terminal 100 having received using the INVITE message with theterminal capability version of the first terminal 100 which has beenpreviously stored therein (S68). According to the results of thecomparison, the second terminal 200 selects and performs one of theterminal capability information exchange procedure and the IMS sessionconnecting procedure. For instance, the second terminal 200 transmitseither a terminal capability information request of the first terminal100 or response with respect to the IMS session connecting request, tothe first terminal 100.

That is, at step S68, if the received terminal capability version of thefirst terminal 100 is equal to the stored terminal capability version ofthe first terminal 100, the second terminal 200 determines the currentterminal capability information of the first terminal 100 is equal tothe terminal capability information from a previous CSI service, andthus sends a 200 OK message to the first terminal 100 in response to theINVITE message (not shown in FIG. 6, but similar to what is shown inFIG. 2).

However, at step S68, if the received terminal capability version of thefirst terminal 100 is different from the stored terminal capabilityversion of the first terminal 100, for example, if the received terminalcapability version is V.1.12 and the stored terminal capability versionis V.0.12, the second terminal 200 determines that the current terminalcapability information of the first terminal 100 is different from theterminal capability information from the previous CSI service. In otherwords, the second terminal 200 determines that the terminal capabilityinformation of the first terminal 100 has been changed. The secondterminal 200 accordingly sends an OPTIONS request message to the firstterminal 100 to thus request the changed terminal capability informationof the first terminal 100 (S69). The OPTIONS request message here mayinclude the terminal capability version of the second terminal 200. Thefirst terminal 100 having received the OPTIONS request message thensends the changed terminal capability information thereof to the secondterminal 200 using an OPTIONS response message, so that the secondterminal 200 can obtain current capability information of the firstterminal 100 for the CSI service.

Accordingly, the second terminal 200 stores the changed terminalcapability information of the first terminal 100 therein as well as thecapability version of the first terminal 100 that corresponds with thechanged terminal capability information of the first terminal 100.Therefore, the present invention maintains consistency between thecurrent terminal capability information of the first terminal 100 andthe terminal capability information of the first terminal 100 stored inthe second terminal 200.

Afterwards, the IMS session is set between the first and secondterminals 100 and 200 through a known IMS session setup procedure andactual data (media) are exchanged therebetween (S70).

At step S64, if the CS call setup message to the second terminal 200includes the terminal capability version of the first terminal 100, thenthe second terminal 200 can compare the received capability version withthe stored capability version of the first terminal 100 and can performthe capability information exchange procedure (if the versions aredifferent) or the IMS session setup procedure directly (if the versionsare the same).

Accordingly, each of the first and second terminals 100 and 200 uses aunique terminal capability version of the other terminal that has beengenerated based upon at least the current terminal capabilityinformation of the other terminal. This prevents the problematicinconsistence between the received terminal capability information andthe pre-stored terminal capability information, and also simplifies asignaling procedure for the combination service connection. Furthermore,since the terminal capability information exchange/transmissionprocedure is performed only when the received capability version valueis different from the prestored capability version of the correspondingterminal, the network load is reduced and the CSI service procedures aremade effective and efficient.

Furthermore, one user generally has a plurality of terminals and theterminals generally use the same public user ID. Here, in a generalcombination service system, each terminal stores terminal capabilityinformation based upon the public user ID (e.g., a URI), and accordinglyit may be difficult to distinguish each terminal capability informationof the plurality of terminals using the same public user ID (e.g., theURI), thereby resulting in some inconsistency in the terminal capabilityinformation. However, the present invention can generate a uniqueterminal capability version based on at least a public user ID of aterminal, a private user ID of the terminal and terminal capabilityinformation of the terminal, or based on at least the public user ID andterminal capability information of the terminal, for example, by usingthe hash function or other encryption/encoding technique. Accordingly,even in cases where one user has a plurality of terminals and uses thesame URI for all the terminals, it is possible to generate differentterminal capability versions having unique values based upon theterminal capability information of each terminal.

Therefore, according to the present invention, each terminal has aunique terminal capability version based upon the current terminalcapability information of the terminal, whereby it is possible todistinguish the plurality of terminals and each terminal capabilityinformation of the plurality of terminals.

In addition, in the related art, since an originating side confirmedpre-stored information of a receiving side, determined whether theterminal capability information was changed (updated), and thenperformed the terminal capability information exchange procedure, whenthe originating side user previously set a call forward function towarda certain terminal among the plurality of terminals belonging to theuser, the terminal capability information exchange procedure wasunnecessarily performed.

However, in the present invention, if there is a change in the terminalcapability version during a call setup or a session setup, a certainside (i.e., the originating side or the receiving side) having receivedthe terminal capability version of the other side compares the receivedterminal capability version with a pre-stored terminal capabilityversion to determine whether the terminal capability information hasbeen changed. Accordingly, the related art problem, which may be causedwhen using an additional service such as a call exchange, can be solved.

FIGS. 7 and 8 illustrate a method for performing a combination serviceusing a terminal capability version according to a third embodiment ofthe present invention. As illustrated in FIGS. 7 and 8, the thirdembodiment addresses a situation when a combination service is performedbetween at least a first user and a second user, and the second user hasa plurality of terminals using the same public use ID associated withthe second user. The method of FIGS. 7 and 8 includes the method ofgenerating a unique terminal capability version as discussed above. Themethod of FIGS. 7 and 8 can be implemented in the system and device ofFIGS. 1 and 3 or in other similar or suitable device/system. Theprocesses to be performed by the terminal 100 or 200 can be performedand/or controlled by the controller 150 of the terminal 100 or 200.

As illustrated in FIGS. 7 and 8, in a system for performing thecombination service according to the present invention, the first useruses the first terminal 100, and the second user uses a plurality ofterminals 200 designated here as a 2-1 terminal 210 and a 2-2 terminal220 as examples. The 2-1 and 2-2 terminals 210 and the 220 use the samepublic user ID, for example, a URI. In the method for performing thecombination service illustrated in FIGS. 7 and 8, when the combinationservice is a CSI service, a CS call is first set and thereafter an IMSsession is set. Furthermore, in the method of FIGS. 7 and 8, the seconduser has previously set a call forward function for forwarding incomingcalls toward the 2-2 terminal 220. In this example, the terminalcapability information of each of the 2-1 terminal 210 and the 2-2terminal 220 is not changed during CSI services while the first terminal100 dynamically updates its terminal capability information. Otherscenarios are possible and the present invention applies equallythereto.

Assume that the first user's first terminal 100 has previously performeda CSI service with the second user's 2-2 terminal 220, and accordingly apublic user ID, terminal capability information and a terminalcapability version of the other terminal have already been stored ineach of the first terminal 100 and the 2-2 terminal 220.

Afterwards, the first terminal 100 performs a CSI service with thesecond user's 2-1 terminal 210. Accordingly, the public user ID, theterminal capability information and the terminal capability version ofthe other terminal, all of which are exchanged during a CSI serviceconnection setup, are stored in each of the first terminal 100 and the2-1 terminal 210 (S71).

That is, the first terminal 100 stores therein the public user ID, theterminal capability information and the terminal capability version allof which are related to the 2-1 terminal 210, and also stores thereinsuch information related to the 2-2 terminal 220. Here, the terminalcapability version of the first terminal 100 is 1000 0100, for example,whereas the capability versions of the terminals 210 and 220 arerespectively 0010 1010 and 1000 1001, for example. Since the capabilityversions of the terminals 210 and 220 can be generated based on theterminal capability information with or without the public user IDand/or private user ID as discussed above, each capability version(value) will be unique.

Afterwards, when the terminal capability information of the firstterminal 100 is changed, e.g., due to attaching multimedia devices suchas camera thereto or detaching the devices therefrom, the first terminal100 uses at least its changed terminal capability information tore-generate a unique terminal capability version (S72). Here, the newlygenerated terminal capability version of the first terminal 100 is 10000101, for example.

When the first terminal 100 having the changed terminal capabilityinformation desires to perform another CSI service with the 2-1 terminal210, the 2-1 terminal 210 determines that the current terminalcapability information of the first terminal 100 has been changed basedupon the changed terminal capability version of the first terminal 100.That is, the terminal 210 compares the received terminal capabilityversion of the first terminal 100 with the previously stored version tomake this determination. The 2-1 terminal 210 then requests and receivesthe changed terminal capability information of the first terminal 100therefrom, e.g., using the OPTIONS request, etc. (S73).

Thereafter, the second user registers a call forward function in orderto forward any calls received at the 2-1 terminal 210 toward the 2-2terminal 220 (S74 and S75). For instance, the second user (the 2-2terminal 220) registers the call forward request in the second IMS corenetwork 410, whereby call forward function setting information(information associated with the call forward function) is generated andstored appropriately. In another embodiment, the 2-1 terminal 210registers the call forward request in the second IMS core network 410,whereby call forward function setting information (informationassociated with the call forward function) is generated and storedappropriately.

Thereafter, when the first terminal 100 desires to perform a CSI servicewith the second user, e.g., the 2-1 terminal 210, the first terminal 100sends a CS call setup message (e.g., a SETUP message) directed to thesecond user's 2-1 terminal 210. This call setup message may include thecurrent terminal capability version of the first terminal 100, such as1000 0101, for example.

Because the call forward function has been registered, the second IMScore network 420 then sends the call setup message to the second user's2-2 terminal 220 by use of the registered call forward function (S76).

The 2-2 terminal 220 then sends to the first terminal 100 a connectionmessage CONNECT in response to the received call setup message (S77).The connection message CONNECT may include the current terminalcapability version of the 2-2 terminal 220, such as 1000 1001, forexample. Accordingly, the CS call is set up between the first terminal100 and the 2-2 terminal 220.

The first terminal 100 compares the received terminal capability versionof the 2-2 terminal 220 with the previously stored terminal capabilityversion of the 2-2 terminal 220. The first terminal 100 then selects andperforms the terminal capability information exchange procedure ordirectly the IMS session connection setup procedure according to theresults of the comparison (S78).

That is, if at step S78 it is determined that the received terminalcapability version of the 2-2 terminal 220 is different from the storedterminal capability version of the 2-2 terminal 220, the first terminal100 determines that the terminal capability information of the 2-2terminal 220 has been changed after performing the previous CSI service,and thus sends an OPTIONS request message to the 202 terminal 220 andexchanges (or receives) the terminal capability information therebetween(S82 and S83). On the other hand, if the received terminal capabilityversion of the 2-2 terminal 220 is determined at step S78 to be equal tothe stored terminal capability version of the 2-2 terminal 220, thefirst terminal 100 determines that the terminal capability informationof the 2-2 terminal 220 has not been changed and proceeds directly to anIMS session setup procedure without performing the terminal capabilityinformation exchange procedure (S86).

The 2-2 terminal 220, on the other side, compares the received terminalcapability version of the first terminal 100 with the previously storedterminal capability version of the first terminal 100, and selectivelyperforms the terminal capability exchange procedure with the firstterminal 100 based on the determination results (S79). If the recentlyreceived terminal capability version of the first terminal 100 is notequal to the stored terminal capability version of the first terminal100, e.g., if the received terminal capability version is 1000 0101 andthe stored terminal capability version is 1000 0100, for example, thenthe 2-2 terminal 220 determines that the current terminal capabilityinformation of the first terminal 100 has been changed after performingthe previous CSI service. The 2-2 terminal 220 accordingly determines toperform the terminal capability information exchange procedure with thefirst terminal 100 in order to update the terminal capabilityinformation of the first terminal stored in the 2-2 terminal 220 to bethe same as the actual (changed) terminal capability information of thefirst terminal 100. The terminal capability information exchangeprocedure can be started by sending an OPTIONS request message from the2-2 terminal 220 to the terminal 100 (S80).

The first terminal 100 having received the OPTIONS request message sendsits changed terminal capability information using an OPTIONS responsemessage (S81). The OPTIONS response message may even include theterminal capability version of the first terminal 100. The 2-2 terminal220 receives the changed terminal capability information of the firstterminal 100 through the OPTIONS response message and then storestherein the received information.

Afterwards, the first terminal 100 sets the IMS session with the 2-2terminal 220 according to a known session setup procedure (S86) andexchanges media data therebetween according to the CSI service (S87).

The present invention uses the terminal capability version to determinewhether or not the terminal capability information has changed, andrequests the terminal capability information from only the terminalhaving the changed terminal capability information based on thedetermination. Hence, according to the present invention, steps S80 andS81 and/or steps S82 and S83 for requesting and receiving terminalcapability information are not performed if the terminal capabilityinformation has not changed, which is determined by comparing thecapability versions (values).

In addition, when the terminal capability information related to atleast one terminal has been changed after performing the previous CSIservice between two terminals which have performed the CSI servicebefore, the terminal capability version can be used to correctlydetermine whether the terminal capability information of each terminalhas been changed, whereby the terminal capability information stored ina local area (i.e., the storage unit) of each terminal can be updated tothus prevent the unnecessary signaling procedures (e.g., S84 and S85)during the IMS session setup. For instance, the process of sending anINVITE message based on inaccurate capability information of anotherterminal and thus receiving a failed response (S84 and S85) can beavoided since each terminal will always have the accurate capabilityinformation of other terminals to be in communication with.

The inventive concepts of FIGS. 7 and 8 are equally applicable to asituation where an IMS session is first set up and then a CS call set up(e.g., FIG. 5) among terminals, some of which have the same public userID.

Thus, when one user has a plurality of terminals using the same publicuser ID, unique terminal capability versions different from one anothercan be generated based upon at least the terminal capability informationof each terminal and the generated terminal capability versions can beexchanged during a call setup or a session setup. Accordingly, thepresent invention enables an originating side terminal and a receiving(terminating) side terminal to determine whether or not the terminalcapability information of the other terminal has been changed.Therefore, related art problems, which may occur when using anadditional service such as a call forward, can be addressed.

According to the preferred embodiments of the present invention, eachterminal can be a UE or a mobile terminal (but not limited thereto),which is capable of providing a CS, a SIP-based service such as an IMS,a combination service such as a CSI, etc. Examples of the terminal canbe, but are not limited to, a PT (Push To) client, a mobile phone, a UE(user equipment) for UMTS or the like, an MS (mobile station) for GSM orthe like, a laptop computer, a PDA (personal digital assistant), varioustypes of mobile terminals. A PT client can be a PTT (Push To Talk)client such as a PoC (Push-to-talk Over Cellular) client, a PTV (Push ToView) client, a PTD (Push to Data) client, etc.

According to the present invention, there are same or similar steps inthe first through third embodiments discussed herein. As such,variations discussed in any one embodiment of the present invention canbe applied to other embodiments of the present invention, as needed.Also, whenever a terminal receives a capability version of anotherterminal that is different from the corresponding previously storedcapability version, the terminal stores the received capability versionas the current capability version of the another terminal. Similarstoring is performed for the terminal capability information of theanother terminal. Moreover, if it is determined during the comparison ofcapability versions that there is no stored terminal capability versionof a target terminal in a terminal, then the terminal can performoperations to request the capability version and/or the capabilityinformation from the target terminal.

The method(s) of the present invention can be implemented in part byusing existing computer programming language. Such computer program(s)may be stored in portable or other types of storages or memories such ashard drive, RAM, ROM, PROM, etc. associated with one or more computersor computer-based devices such as the networks and/or the terminals.Alternatively, such computer program(s) may be stored in a differentstorage medium such as a USB, magnetic disc, optical disc,magneto-optical disc, etc. Such computer program(s) may also take theform of a signal propagating across the Internet, extranet, intranet orother network and arriving at the destination device (e.g., networkserver(s) or terminal) for storage and implementation. The computerprograms are readable using a known computer or computer-based device.

As described above, in the present invention, whenever terminalcapability information of each terminal is changed, a unique terminalcapability version corresponding to the updated terminal capabilityinformation is generated and kept, and a service connection setupmessage can then be sent by including the terminal capability versiontherein. Thereafter, an originating terminal and a receiving(terminating) terminal respectively can compare the stored terminalcapability information of the other terminal and the received terminalcapability version of the other terminal, whereby whether or not theterminal capability information of the other terminal has been changedcan effectively be determined.

In addition, in the present invention, when the change in the terminalcapability information has been confirmed based upon the receivedterminal capability version of another terminal, one terminal requeststhe changed terminal capability information from the another terminal ofwhich terminal capability information has been changed and receives therequested information therefrom, thereby maintaining consistentinformation in the local storage unit of the one terminal and reducingsignaling processes performed for a terminal capability informationexchange procedure.

Furthermore, in the present invention, the signaling for a serviceconnection setup can be simplified by confirming whether the terminalcapability information of the other terminal has been changed andselectively performing one of a terminal capability information exchangeprocedure and a service connection setup procedure according to theresults of the confirmation.

In the present invention, even when one user has a plurality ofterminals using the same public user ID and has registered a callforward function of a receiving side terminal, both the originatingterminal and the receiving terminal can respectively confirm whether ornot the terminal capability information of the other terminal(s) hasbeen changed, to thus eliminating the use and reliance of inaccurate orold information stored in terminal storage units.

As the present invention may be embodied in several forms withoutdeparting from the spirit or essential characteristics thereof, itshould also be understood that the above-described embodiments are notlimited by any of the details of the foregoing description, unlessotherwise specified, but rather should be construed broadly within itsspirit and scope as defined in the appended claims, and therefore allchanges and modifications that fall within the metes and bounds of theclaims, or equivalents of such metes and bounds are therefore intendedto be embraced by the appended claims.

What is claimed is:
 1. A terminal capable of providing a circuit switched (CS) service, a session initiation protocol (SIP)-based service, or a CSI service which is a combination of the CS service and an IP multimedia subsystem (IMS), the terminal comprising: a controller to receive a terminal capability version of at least one target terminal, to compare the received terminal capability version with a previously stored terminal capability version of the at least one target terminal, and to request for terminal capability information of the at least one target terminal if the received terminal capability version of the at least one target terminal is different from the previously stored terminal capability version of the at least one target terminal based on the comparison result, wherein if the received terminal capability version of the at least one target terminal is the same as the previously stored terminal capability version of the at least one target terminal, then the controller bypasses requesting for the terminal capability information of the at least one target terminal from the at least one target terminal, and proceeds with a CS or IMS process, and wherein the terminal capability version identifies a version of capabilities of the at least one target terminal.
 2. The terminal of claim 1, wherein the controller requests for the current terminal capability information of the at least one target terminal using an OPTIONS message.
 3. The terminal of claim 1, wherein the controller receives the terminal capability version of the at least one target terminal from the at least one target terminal during a CS call set-up or an IMS session set-up.
 4. The terminal of claim 1, wherein the terminal capability version of the at least one target terminal is a unique value generated based on at least the terminal capability information of the at least one target terminal.
 5. The terminal of claim 1, wherein the at least one target terminal includes a second terminal and a third terminal for selectively exchanging their terminal capability information with the controller, and the third terminal is designated by the second terminal to communicate directly with the terminal based on forward function setting information.
 6. The terminal of claim 5, wherein when the controller transmits a setup request message intended for the second terminal based on the forward function setting information, the third terminal receives the setup request and transmits a terminal capability version of the third terminal to the controller.
 7. The terminal of claim 6, wherein the controller compares the received terminal capability version of the third terminal with a stored terminal capability version of the third terminal, and determines whether to request for terminal capability information of the third terminal based on the comparison result.
 8. The terminal of claim 7, wherein the controller requests for the terminal capability information of the third terminal, if the received terminal capability version of the third terminal is different from the stored terminal capability version of the third terminal; and wherein the controller bypasses requesting for the terminal capability information, and proceeds with carrying out a requested service, if the received terminal capability version of the third terminal is the same as the stored terminal capability version of the third terminal.
 9. The terminal of claim 1, wherein the terminal capability version of the at least one target terminal has a value in a UCV-XX (UE capability version-XX) form where XX is a 2-digit hexadecimal number.
 10. A method for providing a circuit switched (CS) service, a session initiation protocol (SIP)-based service, or a CSI service which is a combination of the CS service and an IP multimedia subsystem (IMS), the method comprising: receiving, by a terminal, a terminal capability version of at least one target terminal; comparing, by the terminal, the received terminal capability version with a previously stored terminal capability version of the at least one target terminal; and sending a message for requesting for terminal capability information of the at least one target terminal from the at least one target terminal, if the received terminal capability version of the at least one target terminal is different from the previously stored terminal capability version of the at least one target terminal based on the comparison result, wherein if the received terminal capability version of the at least one target terminal is the same as the previously stored terminal capability version of the at least one target terminal, then the requesting for the terminal capability information of the at least one target terminal from the at least one target terminal is bypassed, and the method proceeds with a CS or IMS process, and wherein the terminal capability version identifies a version of capabilities of the at least one target terminal.
 11. The method of claim 10, wherein the message is an OPTIONS message.
 12. The method of claim 10, wherein the terminal capability version of the at least one target terminal is received from the at least one target terminal during a CS call set-up or an IMS session set-up.
 13. The method of claim 10, wherein the terminal capability version of the at least one target terminal is a unique value generated based on at least the terminal capability information of the at least one target terminal.
 14. The method of claim 10, wherein the at least one target terminal includes a second terminal and a third terminal for selectively exchanging their terminal capability information with the terminal, and wherein if the second terminal designates the third terminal to communicate directly with the terminal based on forward function setting information, and then if the terminal transmits a setup request message intended for the second terminal, then the method further comprises: receiving, by the third terminal, the setup request from the terminal based on the forward function setting information; and transmitting, by the third terminal, a terminal capability version of the third terminal to the terminal in response to the setup request.
 15. The method of claim 14, further comprising: comparing, by the terminal, the received terminal capability version of the third terminal with a stored terminal capability version of the third terminal; and determining, by the terminal, whether to request for terminal capability information of the third terminal based on this comparison result.
 16. The method of claim 15, wherein the determining step determines to request for the terminal capability information of the third terminal, if the received terminal capability version of the third terminal is different from the stored terminal capability version of the third terminal; and wherein the determining step determines to bypass requesting for the terminal capability information, and the method proceeds with carrying out a requested service, if the received terminal capability version of the third terminal is the same as the stored terminal capability version of the third terminal.
 17. The method of claim 10, wherein the terminal capability version of the at least one target terminal has a value in a UCV-XX (UE capability version-XX) form where XX is a 2-digit hexadecimal number.
 18. A method for providing a circuit switched (CS) service, a session initiation protocol (SIP)-based service, or a CSI service which is a combination of the CS service and an IP multimedia subsystem (IMS), the method comprising: exchanging, by a first terminal, a capability version of the first terminal and a capability version of a second terminal during a session or connection with the second terminal, updating, by the first terminal, the terminal capability version of the first terminal if the first terminal's capability information is changed; transmitting, by the first terminal, an INVITE message for an IMS session setup or CS call setup message for a CS call between the first terminal and the second terminal, the INVITE message including the updated capability version of the first terminal or the CS call setup message including the updated capability version of the first terminal; comparing, by the second terminal, the received terminal capability version of the first terminal with a stored terminal capability version of the first terminal which is received in the exchanging step; and selectively performing, by the second terminal, a terminal capability information request procedure if the received terminal capability version of the first terminal is different from the exchanged terminal capability version of the first terminal based on the comparison result, wherein the selectively performing step includes: not performing, by the second terminal, the terminal capability information request procedure, and proceeding with the IMS session setup and then a CS call setup for a current CSI service, if the comparison result indicates that the received terminal capability version of the first terminal is the same as the stored terminal capability version of the first terminal.
 19. The method of claim 18, wherein the terminal capability request procedure uses a SIP OPTIONS message.
 20. The method of claim 18, wherein in the storing steps, the terminal capability version of the first terminal is a unique value generated based on at least the terminal capability information of the first terminal, and the terminal capability version of the second terminal is a unique value generated based on at least the terminal capability information of the second terminal.
 21. The method of claim 18, wherein the capability version of at least one of the first terminal and the second terminal has a value in a UCV-XX (UE capability version-XX) form where XX is a 2-digit hexadecimal number. 